In mobile telephone systems the use of affinity groups is becoming popular. In Motorola's iDEN system, for example, mobile users are associated with affinity groups (called fleets). Within each fleet, a user can be a member of one or more groups. The iDEN system allows for very efficient group calls, where all members share the same communication resource, such as a Dispatch Application Processor (DAP) and voice Packet Duplicator (PD). When group members are in the same cell, they even share the same channel. Much of the group call efficiency is obtained by assigning all new members of a fleet to the DAP that already contains other fleet members. That way all fleet members will be controlled by the same DAP.
When the first member of a fleet roams into an urban system, no DAP has yet been assigned to the fleet, and one must be selected. Prior art systems have assigned the fleet to the DAP which has the lightest load at the time of the assignment. While this assignment method generally has worked well for small fleets, it can potentially cause problems when very large fleets exist on a system. Furthermore, users increasingly want to form affinity groups which cross fleet boundaries. For example, a taxi driver may want to be a member of one or more taxi groups, as well as his family group, his church group, and a local crime watch group.
Thus, what is needed is a method and apparatus for assigning a mobile station to a communication resource of a plurality of communication resources. The method and apparatus preferably will take into account the excess capacity of the communication resource and the potential load that can result from the assignment, and will select the communication resource based upon a total affinity strength between the mobile station and the communication resource.